1. Field of the Invention
The present invention relates to a platemaking method, a platemaking device, a printing press, and a printing plate, and more particularly to a printing plate that is made by applying laser engraving to a flexographic plate, for example.
2. Description of the Related Art
Printing letterpress is widely adopted in the field of printing, such as flexographic printing, and particularly in recent years, the flexographic printing has received widespread attention as an eco-friendly printing method.
In the flexographic printing, printing is performed by using a soft and flexible plate and ink (such as water-based ink, and UV ink). The plate used in the flexographic printing is deformed in accordance with printing pressure (pressed amount) due to its flexibility. Accordingly, a flexographic printing plate enables favorable transfer printing to be applied also to a printing medium, such as corrugated cardboard whose surface has asperities, by properly following the surface to be brought into close contact with the surface.
Japanese Patent Application Laid-Open No. 2011-224878 (hereinafter referred to as PTL 1) discloses printing letterpress to be adopted in flexographic printing. The printing letterpress has a plurality of kinds of dot main protrusion each of whose height in a printing surface is different from each other in a tint area. In PTL 1, local expansion of a small dot is avoided to eliminate occurrence of non-printing failure near a solid portion, thereby eliminating instability in printing pressure caused by reducing height of a part of the dot protrusions.
Japanese Patent Application Laid-Open No. 2012-074281 (hereinafter referred to as PTL 2) discloses a printing plate for preventing a transfer area formed on a surface of an object to be transferred by transferring a pattern area of the printing plate from being formed in a trapezoid shape stretched from the pattern area. In the printing plate, there is provided a pattern area reduced from pattern area data, and in the pattern area, a reduction ratio of a portion existing on a front end side in a rotation direction of a plate cylinder, to which transfer printing is to be applied earlier, is lower than a reduction ratio of a portion existing on a rear end side therein, to which the transfer printing is to be applied later.